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J. F. IOOMEY AND 0. s. DEMAREST. AUTOMATIC TRANSMISSION CONTROLLINGMEANS.

APPLICATION FILED OCT. I6, I917.

P tented Jul -12, 1921. 4 SHEETSSHEET I.

' M M J AQW? W LIMKWI Z *IF 2* *IUr I 1 T W AAA? 1' VII Maya'izal f LAVAVAVL v INVENTORS J. F. TOOM'EY AND 0. s. DEMAREST.

AUTOMATIC TRANSMISSION CONTROLLING MEANS.

v A PLICATION FILED 001116. 19]]. I 1,3 4,579; Patented July 12,1921.

4 SHEETS-.SHEET 2.

INVENTORS 2 ioamgyg CJfiemarast ff a ATTORNEY J. F. TOOMEY AND 0. s.DEMAREST. AUTOMATIC TRANSMISSION CONTROLLING MEANS.

APPLICATION FILED OCT. 16, I917. I

Patented July 12, 1921.

4 SHEETS-SHEET 3- %/7%\ ATTORNIE Y J. F. IOOMEY AND 0. s. DEMAREST.AUTOMATIC TRANSMISSION-CONTROLLING MEANS.

APPLICATION FILED OCT. 16. I9I7- I Patented July 12, 1921.

4 SHEETS-SHEET 4.

I INVENTORS ATTORNEY plugs P and P adapted to be inserted in any of thejacks of the lines. Vhile but one repeater is illustrated, it will beunderstood, of course, that as many repeaters will be rovided as trafficconditions may require. Jach repeater comprises a pair of amplifiersherein illustrated as vacuum tube amplifiers A and A, although theamplifiers may be of any other type such as, for instance, the so calledmechanical repeater. The amplifiers A and A are provided with inputcircuits 10 and 10 respectively, said input circuits being connected topotentiometers P and P., The potentiometers consist of resistanceelements from various points of which connections are led throughsuitable controlling means to the'input circuits of the amplifiers. Thecontrolling means as illustrated, consists of a set of four controllingrelays 14, 15, 16 and 17, said relays being under the joint control ofthe repeater, and the line or lines with which it is associated. Thepotentiometers are inductively connected through induction coils 11 and11 with input brid es 12 and 12' connected across the line conductorsextending to the plugs P and P Individual to lines L L and L arebalancing artificial lines N N 2 and N Similarly artificial lines N Nand N are individual to lines L L and L,. In order to balance lines ofthe type of lines L and L" an artificial line RN, common to all of saidlines, but individual to the repeater R is provided. Similarly anartificial line RN individual to the repeater R- is provided to balancelines of the type of lines L and L' In order to select and connect tothe repeater an artificial line suitable for balancing a transmissionline, to which the calling end of the repeater is connected, a se lectorswitch SS is provided. This selector switch is of the type illustratedand described in the application of J. F. Toomey and C. S. Demarestabove referred to, and is arranged to actuate connecting relays 18, 19,20, 21, 22, etc., to connect the proper artificial line to the repeater.In actual practice, a similar arrangement would be provided for theanswering end of the repeater, but in order to illustrate two types ofselecting devices a set of selecting relays, including connecting relays23, 24, 25, 26, 27, etc., is shown associated with the answering end ofthe repeater. These selecting and connecting relays operate to select asuitable artificial line and connect the same to the repeater in themanner described in the repeater R, the

plug P, is inserted in jack J 1 and the plug is inserted in jack J A.circuit is thereby completed over sleeve high resistance of the windingof relay 28.

Similarly a circuit is closed over the sleeve contacts. of plug P andjack J from battery, winding of relay 30, sleeve contacts of plug P jackJ and winding of relay 31 to ground. He-

lay 30 is energized, but relay 31, like relay 29, is marginal and doesnot pull up over this circuit. The operator may now actuate acontrolling key by throwing it to the right, whereupon battery isconnected through a low resistance to the sleeve contact of plug I overcontact 32 of said key. Relay 29 is now energized, and in pulling up itsarmature connects ground to the first' contact of switch SS over acircuit from ground, contact of relay 29, winding and back contact ofrelay 33, lower back contact and winding of relay 18 to the firstcontact of switch SS. Upon actuating key K, a circuit was also closedfrom ground over the front contact of relay 28, contact 34 of key K,point 65, where the circuit divides, one path continuing through thewinding of releasing magnet RM to battery, the other path continuingthrough the winding of. relay 35, lower back contact of relay 36, righthand back contact of test relay 37, winding of stepping ma net SM tobattery. The releasing magnet \M is so arranged that upon beingenergized it produces no eltect upon the switch, butnpon being releasedit a'ctuates a mechanism whereby the switch is restored to normal, if ithas been previously advanced out of its normal or zero position. Uponthe energization of relay 35 a circuit is closed over the front contactof said relay through the winding'of relay 36 whereby said relay isenergized. Relay 36 at its upper front contact closes'a circuit fromground over the upper front contact of relay 36, right hand back contactand winding of relay 38 to battery. Relay 38 is thereby energized and atits right-hand front contact closes a locking circuit which extends overthe left-hand back contact of test relay 37. Relay 38 at its left-handfront contact applies a ground to the zero contact of switch SS and allsimilar switches so that the test relays of all. other switches will beenergized to prevent the actuation of such switches. The test relay 37of switch SS is not, however, energized at this time as the steppingmagnet SM upon being energized advan es the switch one step so that itswiper 39 rests upon the first contact before relay 38 is energized.Relay 36 upon being energized also closes the circuit from ground overits upper front contact and over the right-hand back contact and windingof relay 4() to battery. Relay 40 upon being energized at its righthandfront contact closes a locking circuit over the front contact of relay28 to ground. The operations resulting from'the energization of relay.40 will be later described.

Relay 36, upon being energized, at its lowercontact opens the circuitpreviously traced through relay 35 and stepping: magnet SM, so thatrelay 35 and stepping mag; net SM are denergized. The deenergization ofrelay 35 opens the circuit of relay 36 whereby the circuit previouslytraced throughrelay 35 and stepping magnet SM is again closed, providedthe test relay 37 has not been energized in the meantime. It will thusbe seen that the relay 36 acts as a vibrating relay to open and closethe circuit of stepping magnet SM whereby the switch is advanced step bystep until its wiper rests upon a grounded contact. In the case nowbeing described the first contact was grounded so that at the end of thefirst step a 'circuit was closed from ground over the front contact ofrelay 29, windingand back contact of relay 33, lower back contact andwinding of relay 18, first contact and wiper 39 of switch SS, throughthe winding of test relay 37 .to battery. Test .relay 37 istherebyenergized and at its right hand contact opens and holds open thecircuit of the stepping magnet SM. At its left-hand contact itopens thelocking circuit previously traced for the relay 38 whereby saibl relayis denergized and removes the ground from zero contacts of the switchesso that other switches may now be actuated if desired.

Relay 3 upon being energized, closes a locking "circuit from batteryover its left hand front contact through the winding of said relay andover the contact of relay 29 to round. x

elay 18, upon ,bein energized, closes a locking circuit from. atterythrough the winding oftest rela 37, wiper "39 and first contact ofswitch S, winding and lower front contact oflrelay .18, right handwinding of potentiometer controlling relay 14,'

contact 34 of key K and contact of relay 28 to ground. Relays 37 and 18are maintained energized over this circuit and relay His energized.Connectingrelay 18 at its upper contacts connects the artificial line Nto the repeater so that the line. L is now balanced with respect to theinput bridge 12' of, the repeater by means of artificial line N IReturning now to relay 40, said relay upon being energized, at itsmiddle front contact connects battery through a low resistanc to thesleeve contact ofplug P so that relay 31 now receives sufficient currentto energize its winding. A circuit is now closed from ground over thefront contact of relay 31, resistance 64, winding and lower back contactof relay 23, back contact of relay 41, middle winding of relay 14,re-'sistance 42,' back contact --and winding of relay 43, left-hand frontcontact of relay 40, and front contact of relay 30 to battery. Relays23, 14 and 43 are energized over this circuit. Relay 23, upon beingenergized, at its lower front contact closes a locking circuit fromground, front contact of relay 31, resistance 64, winding and lowerfront contact of relay 23, resistance 44 and winding of relay 45 tobattery. Relay 45 is energized over this circuit and at itsupperfrontcontact closes a circuit through winding of relay 41 to openthe initial energizing circuit of connecting relay 23.

It will be understood that a connecting relay,such as 23, correspondingto the line L will be provided for each repeater, and that acorresponding relay such as 41 will also be' provided for each repeater.The

relay 45 at the same time that it closes the circuit of relay 41 closesthe circuits of similar relays corresponding to the'other re-'peaters'so that the circuits of the connecting relays of all otherrepeaters are thereby held open to prevent-a false selection. Relay 43,v

upon being energized, at its contact disconnects its winding from'theselecting circuit previously traced through the windings of relays 43,14 and 31, at the same time locking itself over its front contact.

Relay middle contact'closes a locking circuit from ground through thewinding of'relay 46,

left-hand winding and middle contact of relay 14, left-hand frontcontact of relay 40 and front contact of relay '30 to battery.

Potentiometer controlling relay 14 is now noted that said relay by meansof its middle and left-hand contacts performs functions similar'to thoseperformed by the contacts.

32 and 34 of the key K. This arrangement is provided inorder that theinitiation of the selection for the answering end of the repeater shallbe delayed for a short time with respect to the initiatipnfof theselection at the calling end of the repeater so as to eliminate thepossibility of a false selection.

It will now be seen that Iin'esL, a d; L,-

14, upon being energized, at its are interconnected through therepeaterR, said lines-being balanced by artificial llnes N, and N whichare connected to the answerin and calling ends of the repeaterrespectively by means of connecting relays 23 and 18. Further, the gridsof the amplifiers A and A are connected by means of the potentiometercontrolling relay 14 to the first point of potentiometers P and P, thussecuring the proper amount of transmission gain for this particularconnection.

If for' any reasonthe amplifiers should give toogreat-a degree ofamplification so that singing results, the operator may throw the key Kto the left, instead of the right, thereby closing contacts 47, 48 and49. Contacts 47 and '48 are connected in parallel to contacts 32 and 34,and consequently result in the same sequence of operations as alreadydescribed, so that the same artificial lines will be connected with therepeater and.

the same setting of the potentiometer will be secured. The closure ofcontact 49, however, results in the completion of a circuit from ground,front contact of relay 28, contact 49 of key K and windings of relays 50and 51 to battery. Relay 51', upon being energized, removes a shortcircuit from a resistance 52 serially connected in the output circuit 13of amplifier A and closes a shunt connection across said output circuitthrough the resistance 53. Similarly relay 50 removes a short circuitfrom about'resistance 52 in output circuit 13 of amplifier A and closesa. shunt acrosssaid circuit through the resistance 53. These circuitchanges result in reducing the transmission gain due to the repeater byan amount sufficient to prevent singing. In actual practice theresistances may be ad- .justed so as to secure a decrease intransmission cqulvalent to about five miles of standard cable.

It will be noted that the connection above described results in theenergization of po tentiometer controlling relay 14 only. If, however,the connection had been made between lines L, and L upon operating thekey K a relay 63 corresponding to line L would have been energized,thereby applying ground to the second contact of the switch SS so thatsaid switch would have been advanced two steps and wouldhave restedwithits wiper 39. upon its second contact, thereby energizing connectingrelay 19 to connect artificial line N to the repeater. Relay 19, at itslower contact would have closed a locking circuit extending through theright-hand winding of potentiometer controlling relay 15 instead ofrelay 14, as previously described. On the other hand, relay 31 wouldhave been energized as before, so that the connecting relay 23 wouldhave operated to connect artificial line N to the r pe e and a momentarycircuit would have been closed through the second winding of relay 14 asalready described. Relay 1.4 would thereby be energized and complete alocking circuit through its lefthand winding and the winding of relay46, as already described. Similarly relay 15, upon being energized,closes a locking circuit from ground through the winding of relay 54,through the lift-hand winds ing and middle contact of relay 15, and overthe left-hand contact of relay 40 and contact of relay 30 to'battery.The energization of relays 46 and 54 would result at this time. in nouseful operation. The energization of potentiometer controlling relay 15would result in the connection of the second point of the potentiometersP and P to the grids of the amplifiers over .the right-hand andleft-handcontacts of said relay 15 were-it not for the fact thatpotentiometer relay 1.4 is also energized so that the grids aredisconnected from the second points of the Potentiometers by theright-hand and left-hand contacts of relay 14 and connected over thecorresponding front contacts to the first points of the potentiometers.

It will thus be'seen that when two adjacent potentiometer controllingrelays are actuated the potentiometer connection will be determined bythe lower relay of the two,

the upper relay being without effect.

If the connection had been between line L and line L,,, the actuation ofthe key K would have resulted in the energization of relay 55, wherebythe fourth contact of the switch SS would have been grounded, and uponthe actuation of the'switch, connecting relay 21 would have beenenergized to connect the artificial line RN to the repeater to balancethe line L,,. Relay 21 at 'its lower front contact would have closed acircuit through -the right-hand winding of relay 17, thereby energizingsaid relay so that a locking circuit would have been closed through thewinding of relay 56, left-hand wvindilig and middle contact of relay 17,

points of the potentiometers to the grids were it not for the fact thatthe joint action of relays 46 and 56 results in the closure of a circuitfrom ground over the right-hand contact of relay 56, front contactof'relay- 46 and winding of relay 57 tobattery. Relay 57 is energized overthis circuit,and at its right-hand and left-hand back contacts opens theconnection from the contacts of relay 14 to the grids of the amplifiers,Said relay 7 at its front contacts connects the grids lay 17, so thatthe same series of Operations to the second points of the potentiometer.The actuation of the right-hand and lefthand contact of relay 17 iswithout efiect because the connection thereby closed from the fourthpoints of the potentiometer-s is opened at the contacts of relay 14.

The same result would have been secured had the connection been betweenlines L and L as the actuation of the controlling key K would haveresulted in the energization of relay 58, thereby connecting ground tothe fifth contact of the switch so that the relay 22 would have beenenergized. Relays 21 and 22 have their lower contacts connected inparallel to the right-hand winding of reresults as just described.

Ifthe connection had been between li'nes L and L, the actuation of thecontrolling key would have resulted in the energization of relay 59,thereby connecting ground to the third contact of the switch so thatrelay 20 would have been energized to connect artificial line N, to therepeater, and at its lower front contact to close a circuit through theright-hand winding; of potentiometer con trolling relay 16. heconnection to line L would have resulted in the energization ofpotentiometer relay 14 as already described.

Relay 16, upon being energized would have completed a locking circuitfrom ground through the Winding of relay'60, left-hand winding andmiddle contact of relay 16, lefthand contact of relay and contact ofrelay 30 to battery. Relays 46 and 60 would now be energized, thereby.completing a'circuit from ground over the front contact of relay 60,front contact of relay 46 and through the winding of relay 57 tobattery.

Relay 57 is now energized and at its front contacts connects the secondpoints of the 'potentiometers to the grids of the amplifiers.

Theactuation of the controlling contacts of relays 14 and 16 produces noresult as the grids are now directly under the control of rela 57.

ithout attempting to further describe the various connections with theirpossible results, it is sufficient to say that when any two lines areconnected, one or two of the potentiometer controlling relays areactuated. If only one relay is actuated its right-hand and left-handfront contacts control the connection of the grids to the correspondingpoints of the potentiometer. If two potentiometer controlling relays areactuated, the connection between the grids and the potentiometer will becontrolled by the contacts of the lower relay only, except when relays14 and 17, 14 and 16, or 15' and 17 are actuated at the same time.- Inthe latter case, a circuit is closed over the left-hand contact of relay56 and the contact of relay 54 through the winding of relay 61 tobattery. Relay 61 at its frontcontacts connects the grids to the thirdpoints of the potentiometer. n the other two cases the relay 57 isenergized in the manner already described and connects the grids to thesecond points of the potentiolneters. The only instance in which thefourth points-of the potentiometer will be connected to the grids iswhen the relay 17 is actuated alone.

Upon withdrawing the plugsof the repeater circuits from the jacks, theapparatus will be restored to normal. This operation may be understoodfrom a consideration of the connection previously described betweenlines L and L Upon withdrawing the plug P, from the jack J relays 28 and29- are deenergized. Upon the de'e'nergization of relay 28 the circuitof the releasing magnet FM'of the switch SS is broken at the contact ofsaid relay and the switch SS is thereby restored to normal, breaking thecircuit previously traced through relays 37, 18 and the right-handwinding of relay 14. Relays 37 and 18 are accordingly deenergized. Uponthe deenergization of relay 28 the locking circuit previously tracedthrough relay 40 is broken, and relay 40 is deenergized. Relay 29 uponbeing denergized at its contact opens the locking circuit of relay 33,thereby restoring said relay to normal. Upon withdrawing plug P, fromjack J, relays 30 and 31 are deenergized. Relay 30 at its contact opensthe locking circuit of relay 43 and also opens the locking circuit ofthe left-hand winding of relay 14 and the winding of relay 46. Relays 14and 46 are thereby deenergized and the potentiometer controllingapparatus is restored to normal. Relay 31, upon being deenergized, opensthe locking circuit prevition, the transmission gain due to theconnection of two transmission circuits through a repeater may beautomatically determined by means of the particular circuits connected,thereby eliminating the cost of the potentiometer regulating key, which,with the cost of its installation and cabling is an expensive feature inthe organization heretofore used.

Moreover, the capacity of the switchboard" key shelf would not bereduced so much as at present, as the single lever, repeater control keyrequired by the arrangement just described would take much less roomthan the potentiometer regulating key heretofore used.

Furthermore, no attention need be given by the operator to the selectionof the proper adjustment for each connection, so thatthe work requiredof the operator is considerably reduced. I i

- While the invention has been disclosed as embodied in certain formswhich are considered desirable, it will be understood that it may beembodied in many widely different organizations without departing fromthe spirit of the invention.

What is claimed is:

1. A transmission circuit for transmitting signaling currents, terminalapparatus with which said. circuit may be associated, and meansoperating automatically to so vary the transmission efiiciency of saidcircuit, in accordance with the transmission requirements with respectto the signaling currents of any type of terminal apparatus with whichsaid circuit is associated, that the total transmission equivalent ofsaid transmission circuit and terminal apparatus will be substantiallyconstant regardless of the type of terminal apparatus associated withthe transmission circuit.

2. A transmission circuit for transmitting signaling currents, aplurality of terminating lines with which said transmission circuit maybe associated, and means controlled by said terminating lines to soadjust the transmission efficiency of said circuit, in accordance withthe transmission requirements with respect to signaling currents of theline with which it is associated, that the total transmission equivalentof the circuit and line will be substantially constant regardless of theline with which the transmission circuit is associated.

' ,3. A repeater circuit, terminal apparatus with which said repeatercircuit may be as sociated, and means operating automatically to socontrol the transmission gain of said repeater. circuit, in accordancewith the transmission requirements of the terminal apparatus with whichit is associated, that the total transmission equivalent of the repeaterand associated terminal apparatus will be substantially constantregardless of the type ofterminal apparatus associated with therepeater. x

4. A repeater circuit, a plurality of transmission lines with which saidrepeater circuit may be associated, and. means controlled by saidtransmission lines to so adjust the transmission gain of said repeatercircuit, in accordance with the transmission requirements of the linewith which it is associated, that the total transmission equivalent ofthe re eater circuit and associated line will be substantially constantregardless of the character of the repeater.

5. A repeater, means to determine the amplification of said repeater,terminal apparatus with which said repeater maybe assoline associatedwith the ciated, and means to automatically control said amplificationdetermining means in accordance with the transmission requirements ofthe terminating apparatus with which the repeater is associated.

6. A repeater, adjustable means to determine the amplification of saidrepeater, a plurality of transmission lines with which said repeater maybe associated, and means controlled by said transmission lines to adjustsaid amplification controlling means in accordance with the requirementsof the line with which the repeater is associated.

7. A repeater comprising an evacuated tube provided with a controllingelectrode, a potentiometer associated with said electrode, terminatingapparatus with which said repeater may be associated and means forautomatically adjusting the potentiometer in accordance with therequirements of the terminating apparatus with which the repeater isassociated. I

8. A repeater comprising an evacuated tube including a controllingelectrode, a potentiometer associated with said electrode, a pluralityof transmission lines with which said repeater may be associated, andmeans controlled by said transmission lines to adjust said.potentiometer in accordance with the requirements of the transmissionline with which said repeater is associated.

9. A repeater circuit, a plurality of trans mission lines .with whichsaid repeater circuit may be associated, a plurality of artificial linesfor balancing said transmission lines, iiieans forselecti'ng anartificial line to balance the transmission line with which saidrepeatercircuit is associated and means to automatically control thetransmission efficiency of said repeater circuit in accordance with therequirements'of said transmission line.

10. A repeater circuit, a plurality of trans mission lines with whichsaid repeater circuit may be associated, a plurality of artificial linesto balance said transmission lines, and means controlled by said lines.for selecting an artificial line to balance the transmission line withwhich the repeater circuit is associated and for controlling thetransmission efiiciency of said repeater circuit in accordance with-therequirements of said transmission lines.

11. A repeater circuit, a plurality of transmission lines with whichsaid repeater circuit may be associated, a plurality of artificial linesto balance said transmission lines, and a selecting switch forcontrolling the selection of an artificial line to balance thetransmission line with which said repeater circuit may be associated andfor controlling the transmission efiiciency of said repeater circuit inaccordance with the requirements of the transmission line with which therepeater circuit is associated.

. and a relay selecting circuit for controlling the selection of anartificial line to balance the transmission line with which saidrepeater circuit may be associated and for controlling the transmissionefficiency of said repeater circuit in accordance with the requirementsof the transmission line with which the repeater circuit is associated.

13. A repeater comprising an evacuated tube having a controllingelectrode, a potentiometer in circuit with said electrode, a pluralityof relays for variably controlling the connection between saidpotentiometer and said electrode, a plurality of lines with which saidrepeater may be associated, and means to selectively energize one ofsaid relays in accordance with the line with which the repeater isassociated.

14. A repeater comprising an evacuated tube having a controllingelectrode, a potentiometer in circuit with said electrode, a pluralityof lines with which said repeater may be associated, certain of saidlines being grouped, and a plurality of rela s for variably controllingthe connection 0 said potentiometer to said electrode, certain of saidrelays being individual to groups of lines and responsive to theassociation of the repeater with a line of the group to control saidconnection.

15. A plurality of transmission lines, a repeater circuit forinterconnecting said lines, and a plurality of relays for controllingthe transmission efiiciency of said repeater circuit, each relay havingtwo energizing circuits controlled by the association of opposite endsof the repeater circuit with transmission lines.

16. A plurality of transmission lines of diiferent'types, a repeatercircuit for interconnecting said lines, a plurality of relayscorresponding to different types of lines for controlling thetransmission efliciency of said repeater circuit, a circuit for eachrelay controlled by the association of one end of the repeater circuitwith a transmission line, and another circuit for each relay controlledby the association of the opposite end of the repeater circuit with atransmission line whereby one relay will be energized if the repeatercircuit is associated with lines of the same type, and two relays willbe energized if the repeater circuit is associated with lines ofdifierent types.

17. A transmission circuit, a plurality of terminating lines with whichsaid transmis-.

sion circuit may be associated, means controlled by said terminatinglines to adjust the transmission efficiency of said circuit inaccordance with the requirements of the line with which it isassociated, and means controllable at will to vary the adjustment thusobtained.

18. A transmission circuit, a plurality of terminating lines with whichsaid circuit may be associated, and a plurality of relays for variablycontrolling the transmission efficiency of said circuit, said relaysbeing selectively operated in accordance with the terminating line withwhich the circuit is associated.

19. A transmission circuit, a plurality of terminating lines with whichsaid circuit may be associated, certain of said lines being grouped, anda plurality of relays for variably controlling the transmissionefficiency of said circuit, certain of said relays being individual to.groups of lines and responsive to the association of said circuit witha line of the group to control said connection.

20. A repeater, a plurality of transmission lines of different typeswith which said repeater may be associated, and means controlled hy theline with which said repeater is associated for determining theamplification of the repeater, said means operating so that when therepeater is associated with two lines of difi'erent types, thetransmission gain obtained will be approximately a mean between thevalues of gain suitable for the two types. 7

In testimony whereof we have signed our names to this specification thisninth day of .October, 1917.

JOHN F. TOOMEY. CHARLES S. DEMAREST.

